The problem with blaming obesity on low-fat guidelines

There was a post going around the internet recently called, 12 Graphs That Show Why People Get Fat. It’s definitely interesting, and I think raises many great points. But it also includes one point that is misguided.

#4. “The Obesity Epidemic Started When The Low-Fat Guidelines Were Published“. It’s got a nice graph that shows clearly the introduction of low-fat guidelines in the mid 1970s and the beginning of a rise in obesity also starting in the mid 1970s. And in fairness, they do point out that “correlation doesn’t equal causation”.

Here’s the problem with including low-fat guidelines as a suspected cause for rising obesity rates: The guidelines didn’t result in people eating less fat. Here’s a table of data extracted from the Statistics Canada Publication, Food Statistics 2005 that shows the breakdown of calories, fat, protein, and carbohydrates eaten in 1975 and in 2005:

In the 30 year period from 1976 to 2005, people increased their fat intake by 18%. They also increased their overall food intake and their carbohydrates, but only by 11% each. In other words, since the low-fat food guidelines came out, people didn’t decrease the portion of their diet that is fat: they increased it. Can we really blame a low-fat diet for our rising obesity rates when we haven’t been on a low-fat diet?

Much of the current research about weight management suggests that there isn’t much difference in the long-term success of any diet options, but rather success reflects the ability to follow the guidelines. Which is pretty much what the data above shows for the past 30 years: not following a recommended low-fat diet leads to an increase in obesity. Although I will flag that with “correlation doesn’t equal causation.”